A screen printing apparatus is built into the manufacturing line of a printed circuit board (PCB). The apparatus prints conductive paste or the like on a substrate that is transferred from the upstream side and delivers the substrate to the component mounting device on the downstream side.
For example, as disclosed in Japanese Patent Publication No. 2682145, this kind of screen printing apparatus is configured to receive a substrate one by one by the printing unit that performs print processing thereto, and the apparatus sends the printed substrate to the component mounting device. Moreover, in recent years, as disclosed, for example, in Japanese Patent Application Publication No. 2009-70867, an apparatus that comprises two parallel printing units has been developed. The respective printing units individually receive substrates from the upstream side and perform print processing. Then the respective printing units individually deliver the substrates to the downstream side. Such operations have been achieved by using a so-called dual transfer-type component mounting device in which two substrate transfer lines are provided in one apparatus, and the mounting of components are carried out simultaneously (in parallel) with each transfer line. The aim is to make the printing and component mounting processes efficient by coupling the screen printing apparatus and the component mounting device.
Meanwhile, in order to prevent the substrate and the screen mask from overlapping, a screen printing apparatus is configured to fasten the substrate loaded on the substrate table with a clamp device or the like at the print executing position or below the mask in the vicinity thereof; detect a position gap of the substrate by an image capturing; and correct the position of the substrate table upon overlapping the substrate with the mask at the print executing position. In the foregoing case, since there is a lower volume of the mask in a space where the substrate is raised for the overlap, it is difficult to fasten the camera in that space. Therefore, such an apparatus, as described for example in Japanese Patent Publication No. 2682145, is provided with a camera on the side position of the mask. The apparatus is configured such that the substrate is loaded on the substrate table, the clamped substrate is moved once from the lower position of the mask to the camera position after the substrate is loaded on the substrate table, the imaging of the substrate is then performed, the substrate is returned again to the print executing position, and printing is then performed after overlapping the substrate with the mask. Meanwhile, the apparatus described in Japanese Patent Application Publication No. 2009-70867 is provided with a movable camera. The apparatus is configured such that the camera is temporarily placed between the clamped substrate and the mask at the print executing position in order to image the substrate, and the camera is withdrawn to the side position of the mask, after completing the imaging.
In both of the foregoing configurations, however, a relatively long time is required for the substrate recognition after the substrate is loaded, because the substrate or the camera should be moved between the lower position of the mask and the side position of the mask. Accordingly, this is one impediment of improving the throughput (shortening the cycle time) in a printer.
Meanwhile, in the screen printing apparatus of Japanese Patent Application Publication No. 2009-70867, the substrate loading parts and the substrate unloading parts are offset in a direction (Y axis direction) that is orthogonal to the substrate transfer direction (X axis direction), and a stage for supporting and fastening the substrate is configured to move in the Y axis direction. This is because of the need for the substrate unloading parts to be close to each other so as to interlock them with two substrate transfer lines on a component mounting device side of the substrate transfer lines on the component mounting device.
In this apparatus, however, since the stage has to receive a substrate at a position (receiving position) corresponding to the substrate loading part and the stage has to move to a position (sending position) corresponding to the substrate unloading part to unload the substrate after printing, the stage is unable to receive a subsequent substrate while unloading the preceding substrate. Therefore, this is also an impediment to improving the throughput.